In fabricating corrugated board boxes, a rotary die cutter as depicted in FIG. 14 is typically used. Such a rotary die cutter marks off and punches corrugated board sheets underwent printing processing. Hereinafter, description will now be made in relation to the overview of a rotary die cutter disclosed in Patent Literature 1 with reference to FIG. 14.
A rotary die cutter 200 depicted in FIG. 14 includes a pair of parallel frame 214a (on the operating side) and 214b (on the driving side) which are respectively disposed on the left end and the right end and which are coupled via an upper stay 212 and a lower stay 212 extending the cross direction of the rotary die cutter 200. An anvil cylinder 202 and a knife cylinder 203 that are extending in the cross direction and that have the same diameter are pivotally supported respectively at the upper portion and the lower portion of the frames 214a and 214b. Into the driving-side ends of the cylinders 202 and 203, gears 215 and 216 are respectively fitted and are rotated in synchronization with each other by a non-illustrated gear driving unit, so that the anvil cylinder 202 and the knife cylinder 203 rotate in the different directions in synchronization with each other.
A pair of forwarding rolls 217a and 217b in the same shape are disposed at the upstream of the cylinders 202 and 203, respectively, so that corrugated board sheets 201 are fed into the space between the cylinders 202 and 203. On the outer circumference face of the knife cylinder 203, a blade mount 204, which is normally made by wood and which includes a cutting knife 205 or a creaser knife attached to the mount, is attached.
Corrugated board sheets 201 sequentially forwarded from the previous printing process by the forwarding rolls 217a and 217b are sandwiched between the anvil cylinder 202 and the knife cylinder 203, where the sheets 201 undergo punching or marking off by the cutting knife 205 or the creaser knife.
Patent Literature 1 further discloses fixing means that fixes the blade mount to the knife cylinder. Hereinafter, the configuration of the fixing means is to be detailed with reference to FIG. 15.
In FIG. 15, a number of screw holes 206 are arranged along the circumference direction and the cylinder axis direction at predetermined intervals. Here, the positional relationship of the screw holes 206 to a metal patch 207, which is fixed to the knife cylinder in the axis direction of the knife cylinder 203, is determined to be a constant value.
A pair of fixing rings 208a and 208b are freely fitted to the both end portions of the knife cylinder 203 so as to be slidable in the axis direction of the knife cylinder 203 (indicated by the arrows). The fixing rings 208a and 208b are fixed to the knife cylinder 203 by bolts 211.
As depicted in FIG. 15(C), the entire circumferences of the fixing rings 208a and 208b take forms of rising slope toward the center of the cylinder. The front end and the both side ends of the blade mount fixing the cutting knife 205 take forms of descending slope. In addition, reinforcement metals 210 conforming to the above upward and descending slopes are provided.
The descending slopes of the blade mount 204 forms the same slope angle as the upward slops formed on the rear end of the rectangular-shaped metal patch 207 and the upward slops of the fixing rings 208a and 208b such that the entire faces of the descending slopes are in contact with the entire surface of the corresponding rising slopes.
In order to fix the blade mount 204, the front end of the blade mount 204 is firstly inserted into the slope surface of the metal patch 207 so as to determine the position of the circumference direction, and then the blade mount 204 is fixed to the outer circumference face of the knife cylinder 203 by flush bolt 209.
Next, the fixing rings 208a and 208b on the both side ends are moved toward the center and are inserted and fixed to the both side ends of the blade mount 204. Then, pressing the blade mount 204 via the slope face, the fixing rings 208a and 208b are fixed to the knife cylinder 203 by a number of bolts 211.